Thin film circuit device, manufacturing method thereof, electro-optical apparatus, and electronic system

ABSTRACT

To provide a thin film circuit device in which a three-dimensional circuit structure is realized, a thin film circuit device is formed of a first thin film circuit layer and a second thin film circuit layer laminated to each other. The first thin film circuit layer contains a first thin film circuit provided between an underlayer and a protective layer and a lower connection electrode connected to the first thin film circuit and exposed at a part of the bottom surface of the underlayer. The second thin film circuit layer contains a second thin film circuit provided between an underlayer and a protective layer, an upper connection electrode connected to the second thin film circuit and exposed at a part of the top surface of the protective layer, and a lower connection electrode connected to the second thin film circuit and exposed at a part of the bottom surface of the underlayer. The first and the second thin film circuits are bonded to each other so that the lower connection electrode of the first thin film circuit layer is electrically connected to the upper electrode of the second thin film circuit layer.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates to thin film circuit devices having athree-dimensional thin film circuit and to methods to manufacture a thinfilm circuit device having a three-dimensional circuit structure.

2. Description of Related Art

In semiconductor devices and the like, since high temperature processesand the like are performed when necessary layers and regions are formedon a substrate to form a laminate, selection of members to formsubstrates and laminates may be restricted in some cases. For example,resin films, plastic substrates, and the like are not suitable in a hightemperature process.

Hence, for example, according to Japanese Unexamined Patent ApplicationPublication No. 2002-217391, a peeling and transferring technique hasbeen proposed in which a thin film circuit is formed above a heatresistant first substrate with an isolation layer provided therebetween.A non-heat resistant second substrate is adhered onto this thin filmcircuit. The isolation layer is destroyed so that the thin film circuitis transferred to the second substrate side.

SUMMARY OF THE INVENTION

Semiconductor devices and/or display devices having a three-dimensionalcircuit structure may be formed by laminating thin film circuits usingthe peeling and transferring technique described above.

However, in order to realize a three-dimensional circuit structure, wireconnection between upper and lower thin film circuit layers formed by apeeling and transferring process and electrical connection betweenlaminated films in the vertical direction must be realized. In thepeeling and transferring technique performed using substrates, describedabove, non-electrical conductive peeling layers, adhesive layers,protective layers, and the like are used to form a laminate. However,wire connection between thin film circuits laminated to each other inthe vertical direction has not been proposed.

Accordingly, the present invention provides a manufacturing method of athin film device, which uses a peeling and transferring techniquecapable of laminating thin film circuit layers and of simultaneouslyforming electrical connection therebetween.

In addition, the present invention provides a thin film device torealize a three-dimensional circuit structure.

Furthermore, the present invention provides an electronic system usingthe thin film device described above.

To these ends, a thin film circuit device of an aspect of the presentinvention, includes: an underlayer; a thin film circuit layer formed onthe underlayer and functioning as an electrical circuit; and aconnection electrode which penetrates a part of the underlayer so as tobe exposed approximately flush with a surface of the underlayer at theside opposite to the thin film circuit layer and which connects the thinfilm circuit layer to an exterior circuit.

According to the structure described above, since the connectionelectrode is exposed outside, the thin film circuit layer and theexterior circuit can be connected to each other. Hence thin film circuitlayers can be easily laminated to each other.

The thin film circuit device described above may further include aprotective layer covering at least a part of the thin film circuit layerfor protection; and a connection electrode which penetrates a part ofthe protective layer so as to be exposed approximately flush with asurface of the protective layer at the side opposite to the thin filmcircuit layer and which connects the thin film circuit layer to anexterior circuit. Accordingly, the electrical connection can beperformed at the upper side and the lower side of the thin film circuitlayer.

In addition, a thin film circuit device according to an aspect of thepresent invention, includes: a heat resistant first substrate; a peelinglayer which is formed on the first substrate and which is to be peeledaway by energy applied thereto; an insulating underlayer formed on thepeeling layer; a thin film circuit layer formed on the underlayer; aprotective layer formed on the thin film circuit layer; and a connectionelectrode which penetrates a part of the underlayer to be in contactwith the peeling layer and which is to be exposed to connect the thinfilm circuit layer to an exterior circuit when the peeling layer ispeeled away.

According to the structure described above, a basic thin film circuitlayer can be obtained to form a thin film circuit laminate device whichis composed of a plurality of said thin film circuit layers. When apeeling and transferring process is repeated using the structuredescribed above, a laminate of the thin film circuit layers can beeasily formed.

The thin film circuit device described above may further include aprotective layer between the peeling layer and the underlayer. By thepresence of this protective layer mentioned above, damage done to thethin film circuit layer in a peeling and transferring process, inparticular, damage done to the connection electrode in contact with thepeeling layer can be reduced or prevented.

A thin film circuit device according to an aspect of the presentinvention, includes: a first thin film circuit layer having a first thinfilm circuit formed between an underlayer and a protective layer and alower connection electrode connected to the first thin film circuit andexposed at a part of the bottom surface of the underlayer; and a secondthin film circuit layer having a second thin film circuit formed betweenan underlayer and a protective layer, an upper connection electrodeconnected to the second thin film circuit and exposed at a part of thetop surface of the protective layer, and a lower connection electrodeconnected to the second thin film circuit and exposed at a part of thebottom surface of the underlayer. In the thin film circuit devicedescribed above, the first thin film circuit layer and the second thinfilm circuit layer are laminated to each other. The lower connectionelectrode of the first thin film circuit layer is connected to the upperconnection electrode of the second thin film circuit layer.

According to the structure described above, a basic laminate structurecan be obtained which is composed of a plurality of thin film circuitlayers.

In the thin film circuit device described above, the lower connectionelectrode and the upper connection electrode may be connected to eachother with an anisotropic conductive material or a conductive adhesive.Hence, electrical connection between the thin film circuit layers can beachieved.

The lower connection electrode may be formed approximately flush withthe underlayer. Hence, the bottom surface of the thin film circuit layeris planarized, and as a result, the lamination can be easily performed.

The bottom surface of the first thin film circuit layer and that of thesecond thin film circuit layer may be formed approximately parallel toeach other. Hence, the lamination accuracy of the thin film circuitlayers can be enhanced.

An electro-optical apparatus of an aspect of the present inventionincludes the thin film circuit device described above.

An electronic system of an aspect of the present invention includes theelectro-optical apparatus described above.

A method to manufacture a thin film circuit device, according to anaspect of the present invention, includes: forming a first thin filmcircuit layer above a first circuit-forming substrate with a peelinglayer provided therebetween, the first thin film circuit layer havingone connection electrode on at least a surface thereof; forming a secondthin film circuit layer above a second circuit-forming substrate with apeeling layer provided therebetween, the second thin film circuit layerhaving connection electrodes on one surface and another surface thereof;peeling the first thin film circuit layer from the first circuit-formingsubstrate so that the first thin film circuit layer is transferred to atransfer substrate; bonding the second thin film circuit layer to thefirst thin film circuit layer transferred to the transfer substrate sothat one of said connection electrodes of the second thin film circuitlayer overlaps the connection electrode of the first thin film circuitlayer; and peeling the second thin film circuit layer from the secondcircuit-forming substrate so that the second thin film circuit layer istransferred to the first thin film circuit layer to form a laminate.

According to the manufacturing method described above, a thin filmcircuit device formed of thin film circuit layers laminated to eachother can be manufactured.

In the method to manufacture a thin film circuit device, describedabove, at least one of the first thin film circuit layer and the secondthin film circuit layer may be formed by a process including forming anunderlayer on the peeling layer provided on the circuit-formingsubstrate; forming a thin film circuit on the underlayer; forming acontact hole penetrating a part of the underlayer to expose the peelinglayer; forming an electrode wire between the contact hole and the thinfilm circuit; and forming a protective layer on the thin film circuitand the electrode wire. Hence, a thin film circuit layer provided with aconnection electrode can be obtained as a transfer unit.

The method to manufacture a thin film circuit device, described above,may include: forming a protective layer between the peeling layer andthe thin film circuit layer; and removing the protective layer after thethin film circuit layer is peeled away to transfer. Accordingly, thedamage done to the thin film circuit layer in a peeling and transferringprocess, in particular, the damage done to the connection electrode incontact with the peeling layer can be reduced or prevented.

The protective layer may be formed of a material different from that forthe underlayer of the thin film circuit layer, and for example, a filmmade of silicon nitride or a metal may be used.

The protective layer described above may be formed to have athree-layered structure composed, for example, of an amorphous siliconlayer/an insulating film (silicon oxide or silicon nitride)/an amorphoussilicon layer. In the case described above, the amorphous silicon layerat the lower side (at the circuit-forming substrate side) functions as apeeling layer, and the amorphous silicon layer at the upper sidefunctions as a protective layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic for illustrating a thin film circuit device of anaspect of the present invention, which is formed of thin film circuitlayers laminated to each other;

FIGS. 2A to 2D show a process for manufacturing a thin film circuitlayer;

FIGS. 3A to 3H show a process for illustrating manufacturing steps of athin film circuit layer;

FIGS. 4A to 4E show a process for illustrating manufacturing a thin filmcircuit layer having a connection electrode for connection between thinfilm circuit layers;

FIGS. 5A to 5F show another process for illustrating manufacturing of athin film circuit layer having a connection electrode for connectionbetween thin film circuit layers;

FIGS. 6A to 6F show still another process for illustrating manufacturingof a thin film circuit layer having a connection electrode forconnection between thin film circuit layers;

FIG. 7 is a schematic for illustrating a particular example (organic ELdisplay apparatus) of a thin film circuit device; and

FIGS. 8A to 8F are schematics for illustrating electronic systems usinga thin film circuit device of an aspect of the present invention, thedevice formed by laminating thin film circuit layers to each other.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the exemplary embodiments of the present invention will bedescribed with reference to drawings.

A thin film circuit device of an exemplary embodiment of the presentinvention has a structure in which thin film circuits are laminated toeach other in the vertical direction, and in which, among the circuitsmentioned above, an intermediate thin film circuit present inside thelaminate is formed to have electrodes on the upper and the lowersurfaces thereof for electrical connection. In addition, in the thinfilm circuit device according to the exemplary embodiment of the presentinvention, since an electrode is formed which is exposed at the rearsurface of the thin film circuit, connection with a thin film circuitlocated thereunder and/or an exterior wire can be easily achieved.

In a manufacturing method according to an exemplary embodiment of thepresent invention, a process to manufacture a thin film circuit deviceusing a peeling and transferring technique includes forming a contacthole penetrating an underlayer of a thin film circuit layer, and forminga conductive film in the contact hole using a metal or the like so as beexposed at the bottom surface of the underlayer. This conductive film isused as a rear surface electrode to connect with another thin filmcircuit layer. This rear surface electrode and the underlayer of thethin film circuit layer are formed flush with each other so that therear surface of the thin film circuit layer is flat. Hence thelamination of the layers can be easily performed. Irregularitiesgenerated on a surface of a thin film circuit layer located at the upperside can be reduced or prevented, which irregularities are formed whenthin film circuit layers having irregular surfaces are laminated to eachother.

FIG. 1 is a cross-sectional schematic showing an example of a thin filmcircuit device according to an aspect of the present invention, thedevice having a three-dimensional circuit composed of thin film circuitlayers laminated to each other.

In this figure, a first thin film circuit layer 21 is mounted on atransfer substrate 31 with an adhesive 32 provided therebetween. Asecond thin film circuit layer 22 is mounted on this first thin filmcircuit layer 21 with an adhesive 33 provided therebetween. Furthermore,a third thin film circuit layer 23 is mounted on this second thin filmcircuit layer 22 with an adhesive 34 provided therebetween. Each thinfilm circuit layer has a thin film circuit including at least one of athin film transistor, a diode, a resistor, a capacitor, a wire, and anelectrode and has a predetermined circuit function.

Connection between the thin film circuit layers 21 and 22 is performedwith a lower electrode 211 of the thin film circuit layer 21, an upperelectrode 229 of the thin film circuit layer 22, and an anisotropicconductive material 35 provided between the electrodes 211 and 229.Connection between the thin film circuit layers 22 and 23 is performedwith a lower electrode 221 of the thin film circuit layer 22, an upperelectrode 239 of the thin film circuit layer 23, and an anisotropicconductive material 35 provided between the electrodes 221 and 239. Theanisotropic conductive material 35 has conductive properties in acompressive direction. For example, when conductive particles aredispersed in an insulating elastic material, and the elastic material isthen compressed, the conductive particles are connected to each other,thereby forming an electrical conductive path in the compressivedirection.

The lowermost thin film circuit layer 23 has a lower electrode 231exposed at the bottom surface thereof. An exterior wire, not shown inthe figure, is connected to this lower electrode 231 with a flexibleprinted wire, tab bonding, wire bonding, or the like. The bottomsurfaces of underlayers (212, 222, and 232 described later) carrying thethin film circuits of the individual thin film circuit layers and theexposed surfaces of the lower electrodes exposed at the underlayers areformed to be flush with each other. Accordingly, when the adhesivelayers 32, 33, and 34 adhering between the thin film circuit layers areapplied or formed so as to have flat top surfaces, thin film circuitlayers (underlying substrates) can be laminated so that the individualbottom surfaces are approximately parallel to each other, and as aresult, a three-dimensional circuit structure can be precisely formed.

Alternatively, instead of the anisotropic conductive material 35described above or in addition thereto, a conductive adhesive may beused for connection between the electrodes.

In the exemplary embodiment described above, the thin film circuit layer21 located at the upper side and the thin film circuit layer 23 locatedat the lower side are connected to each other with a thin filmtransistor circuit of the thin film circuit layer 22. However, the thinfilm circuit layers 21 and 23 may be connected to each other only by anelectrode wire. For example, in the case of an electrical power supplywire, the direct connection mentioned above may be applied.

As described above, when thin film circuit layers having electrodesexposed at the upper and the lower surfaces thereof are laminate to eachother, a thin film device having a three-dimensional electrical circuitcan be obtained.

Next, with reference to FIGS. 2 to 4, a method to manufacture a thinfilm device having the above three-dimensional circuit structure will bedescribed.

In order to laminate thin film circuit layers, as shown in FIG. 2A, thelower electrode layer 211 exposed at the underlayer 212 of the thin filmcircuit layer 21 must be formed.

FIGS. 3 and 4 show a process for illustrating forming the thin filmcircuit layer 21.

First, on a transparent circuit-forming substrate 11, having superiorheat resistance and made of quartz glass substrate (SiO₂) or the like, afilm of amorphous silicon (α-Si) is formed as a peeling layer 12 byLP-CVD, sputtering, PE-CVD, or the like. On the film thus formed, as theunderlayer (insulating layer) 212 of the thin film circuit 21, a siliconoxide (SiO₂) film is formed by PE-CVD. On the film thus formed, asilicon (Si) layer 213 is formed as a semiconductor layer by CVD and isthen (poly)crystallized by heat treatment, such as laser radiation. Thissilicon layer 213 is patterned to form an active region of a transistor,a wire, and the like (FIG. 3A).

On the layer thus patterned, a silicon oxide film is formed by thermaloxidation or PE-CVD using TEOS or the like, thereby forming a gateinsulating film 214 (FIG. 3B).

On the gate insulating film 214, a polysilicon layer doped with animpurity is formed by a CVD method or the like, or a metal thin filmlayer primarily composed of chromium, molybdenum, tantalum, aluminum, orthe like is formed by sputtering, followed by patterning, therebyforming a gate electrode and a wire 215 (FIG. 3C).

Next, using a resist 220 and the gate electrode 215 as a mask, forexample, phosphorous ions P⁺at a high concentration, are implanted intothe silicon layer 213 by ion implantation, thereby forming source anddrain regions made of an N-type semiconductor (FIG. 3D). In the samemanner as described above, using a resist 221 and the gate electrode 215as a mask, boron ions at a high concentration are implanted into thesilicon layer 213 by ion implantation, thereby forming source and drainregions made of a P-type semiconductor. In addition, heat treatment isperformed, thereby activating impurities in the source and drain regionsand the wires (FIG. 3E).

On the gate electrodes 215 and the gate oxide film 214, a silicon oxidefilm is formed by a CVD method as an interlayer insulating film 216(FIG. 3F).

Next, the interlayer insulating film 216 is patterned, thereby formingcontact holes. In addition to contact holes in the source and the drainregions of the transistors, a part of the underlayer 212 at which thelower electrode 211 is to be formed is also etched (FIG. 3G). In orderto form the lower electrode 211, said part described above is etcheduntil the peeling layer 12 is exposed.

Subsequently, a film, which is composed, for example, of a metal, suchas aluminum, molybdenum, tungsten, or ITO, or polysilicon heavily dopedwith an impurity, is formed and is then patterned, thereby forming thelower electrode, wire, and source and drain electrodes 217 (FIG. 3H).

Furthermore, as shown in FIG. 4, an interlayer insulating film (SiO₂) ora protective film (PSG) 218 is formed on the laminate thus formed,followed by polishing whenever necessary for planarization (FIG. 4A). Inthis case, as the protective film 218, a film may be formed by applyingan insulating resin using spin coating onto the upper surface of thecircuit-forming substrate 11 provided with wires or the like, so as toform a flat surface. As described above, the thin film circuit layer 21is formed.

Furthermore, the adhesive 32 is uniformly applied onto the upper surfaceof the thin film circuit layer 21 and is mounted on the transfersubstrate 31 (FIG. 4B).

The peeling layer 12 is irradiated with intensive light, such as laserlight, from below the circuit-forming substrate 11, thereby causinginterfacial peeling or interlayer peeling of the peeling layer 12. Forexample, as disclosed in Japanese Unexamined Patent ApplicationPublication No. 10-125930, the reasons for the generation of interfacialand/or interlayer peeling of the peeling layer 12 are believed to be asfollows. The ablation of materials of the peeling layer 12, the emissionof gas components contained in the peeling layer 12, and/or the phasetransformation, such as fusion or evaporation of the peeling layer 12 byirradiation with light, may occur. In this case, the ablation means thephenomenon in that a solid material (in this case, materials forming thepeeling layer 12) absorbing irradiating light is thermally oropto-chemically excited. As a result, atoms present on the surface orinside or molecular fragments formed by chemical bond dissociation areemitted. In this case, the peeling layer 12 is destroyed, the bondingforce thereof is decreased, and as a result, the peeling layer 12 maydisappear in some cases (FIG. 4C).

The thin film circuit layer 21 is peeled away from the circuit-formingsubstrate 11 and is transferred to the transfer substrate 31 (FIG. 4D).In addition, the remaining peeling layer 12 is removed by etching,thereby forming a substrate having the first thin film circuit layer 21shown in FIG. 2A (FIG. 4E).

FIG. 2B shows the second thin film circuit layer 22 formed above thecircuit-forming substrate 11 before a peeling and transferring processis performed. The thin film circuit layer 22 includes the underlayer222, a semiconductor layer 223, a gate insulating layer 224, a gateelectrode and a wiring layer 225, an interlayer insulating film 226,source and drain electrodes 227, a protective film 228, and an upperelectrode 229. The second thin film circuit layer 22 is also formedabove the circuit-forming substrate 11 with the peeling layer 12provided therebetween as is the first thin film circuit layer 21 (seeFIGS. 3 and 4). However, the second thin film circuit layer 22 providedat an intermediate position of the thin film circuit layers thuslaminated is formed to have the upper electrode 229 exposed at theprotective film 228 in addition to the lower electrode 221.

The upper electrode 229 maybe formed as shown in FIG. 4A in which acontact hole is formed in the protective film 218 (corresponding to228), and a film is then formed using a wire material, followed bypatterning. FIG. 2C shows the third thin film circuit layer 23 formedabove the circuit-forming substrate 11 before a peeling and transferringprocess is performed. The thin film circuit layer 23 includes theunderlayer 232, a semiconductor layer 233, a gate insulating layer 234,a gate electrode and a wiring layer 235, an interlayer insulating film236, source and drain electrodes 237, a protective film 238, and anupper electrode 239. The third thin film circuit layer is also formedabove the circuit-forming substrate 11 with the peeling layer 12provided therebetween as is the first thin film circuit layer 21.However, the third thin film circuit layer provided at the bottommostposition of the thin film circuit laminate is formed to have the upperelectrode 239 exposed at the protective film 238 in addition to thelower electrode 231. The upper electrode 239 may be formed as shown inFIG. 4A in which a contact hole is formed in the protective film 218(corresponding to 238), and a film is then formed using a wire material,followed by patterning.

As shown in FIG. 2D, the thin film circuit layers 21 to 23 each formedon the circuit-forming substrate are laminated to each other by apeeling and transferring method.

The thin film circuit layer 22 shown in FIG. 2B is bonded with theanisotropic conductive layer 35 and the adhesive 33 to the bottomsurface of the thin film circuit layer 21 mounted on the transfersubstrate 31 shown in FIG. 2A. The thin film circuit layer 22 isirradiated with laser light from the side of the bottom surface of thecircuit-forming substrate 11 so that the peeling layer 12 is peeledaway, thereby separating the circuit-forming substrate 11 from the thinfilm circuit layer 22. Whenever necessary, the remaining peeling layer12 is removed by etching.

The thin film circuit layer 23 shown in FIG. 2C is bonded with theanisotropic conductive layer 35 and the adhesive 34 to the bottomsurface of the thin film circuit layer 22 mounted at the transfersubstrate 31 side. The thin film circuit layer 23 is irradiated withlaser light from the side of the bottom surface of the circuit-formingsubstrate 11 so that the peeling layer 12 is peeled away, therebyseparating the circuit-forming substrate 11 from the thin film circuitlayer 23. Whenever necessary, the remaining peeling layer 12 is removedby etching.

As described above, a thin film device composed of three-dimensionallyarranged thin film circuits is formed as shown in FIG. 1. The connectionof the thin film device to exterior wires can be performed with thelower electrode 231 exposed at the bottom surface using a solder bump, aflexible wire substrate (tape), wire bonding, and the like.

Amorphous silicon has been described as a material for the peeling layer12 by way of example, and this amorphous silicon may contain H(hydrogen). When hydrogen is contained, since an internal pressure isgenerated in the peeling layer due to emission of hydrogen byirradiation with light, the peeling thereof is facilitated. The contentof hydrogen is adjusted in consideration of film-forming conditions. Forexample, in the case in which a CVD method is used, a gas composition, agas pressure, a gas atmosphere, a gas flow, a gas temperature, asubstrate temperature, input power of light, and the like are taken intoconsideration. In addition, as the peeling layer, silicon oxide or asiliconate compound, titanium oxide or a titanate compound, an organichigh molecular material, a metal, or the like may be optionally used.

When thin film circuit layers are laminated to each other in athree-dimensional manner as described above by a peeling andtransferring method, an electrode for electrical connection may beformed at the bottom surface of the thin film circuit layer. FIGS. 5 and6 each show an example of another thin film circuit layer having anelectrode at the bottom surface of a thin film circuit layer.

In the example shown in FIGS. 5A to 5F, an underlying protective layer13 is formed between the peeling layer 12 and the underlayer 212 and thelower electrode 211. In the figure, the same reference numerals as thosein FIG. 4 designate corresponding elements, and descriptions thereof areomitted.

The underlying protective layer 13 is composed of a silicon nitride(SiN) layer or a metal layer, which is formed of a material differentfrom that for the underlayer 212, and which has functions of reducingthe likelihood or preventing unnecessary components from intruding intothe lower electrode 211 and the underlayer 212 from the peeling layer 12and of reducing the likelihood or preventing the lower electrode 211 andthe underlayer 212 from being damaged by heat and destructive energyapplied to the peeling layer 12 when a peeling and transferring processis performed. The underlying protective layer 13 is removed by etchingas shown in FIGS. 5E and 5F after the thin film circuit layer 21 ispeeled and transferred.

As described above, the underlying protective layer 13 may be etched bya method having a large selectivity between the underlying protectivelayer 13 and the underlayer 212 and/or the lower electrode 211. Forexample, when silicon nitride is used for the underlying protectivelayer 13, phosphoric acid, nitric acid, acetic acid, or a mixed solution(mixed acid) thereof is used to etch the underlying protective layer 13.Since the etching rate of the underlayer 212 composed, for example, of asilicon oxide is low, the underlying protective layer 13 can be fullyremoved by over-etching. In addition, by forming a conductive protectivelayer of chromium, titanium, ITO, or the like on the bottom surface ofthe lower electrode 211, corrosion thereof caused by the etching of theunderlying protective layer 13 may be reduced or prevented.

In the example shown in FIGS. 6A to 6F, protective layers 13 and 14 areformed between the peeling layer 12 and the underlayer 212 and the lowerelectrode 211. In the figure, the same reference numerals as those inFIG. 4 designate corresponding elements, and descriptions thereof areomitted.

The protective layer 13 is an insulating film formed, for example, of asilicon oxide layer or a silicon nitride layer, and the protective layer14 is, for example, an amorphous silicon layer. Of the two amorphoussilicon layers 12 and 14 thus formed, the lower side layer and the upperside layer function as a peeling layer and a protective layer,respectively. The underlying protective layers 13 and 14 are removed byetching, as shown in FIGS. 6E and 6F, after the thin film circuit layer21 is peeled and transferred.

As is the case described above, the underlying protective layer 13 maybe etched by a method having a large selectivity between the underlyingprotective layers 13 and 14 or between the underlying protective layer14 and the underlayer 212 and/or the lower electrode 211. For example,when silicon oxide is used for the underlying protective layer 13, andan amorphous silicon layer is used as the underlying protective layer14, a solution containing fluoric acid may be used to etch theunderlying protective layer 13. Since the etching rate of the underlyingprotective layer 14 is low, the underlying protective layer 13 can befully removed by over-etching. In addition, when the underlyingprotective layer 14 is etched, for example, dry etching may be performedusing a gas containing CF₄. Since the etching rate of the underlayer 212formed, for example, of silicon oxide is low, the underlying protectivelayer 14 can be fully removed by over-etching. In addition, by forming aconductive protective layer of chromium, titanium, ITO, or the like onthe bottom surface of the lower electrode 211, corrosion thereof causedby the etching of the underlying protective layer 14 may be reduced orprevented.

FIG. 7 shows a particular example of a thin film circuit layer, in whichan inverted type organic EL display element is formed on a first thinfilm circuit layer. On a peeling layer provided on a circuit-formingsubstrate not shown in the figure, a thin film transistor 311, a wire312, an anode 313, a bank 314, a light-emitting layer 315, a cathode316, and the like are provided to form a thin film circuit layer. Thisthin film circuit layer is peeled and transferred onto the transfersubstrate 31. Since the thin film circuit layer 21 is transferred ontothe transfer substrate 31, a lower electrode 317 is exposed at anunderlayer located at the bottom surface.

Since the exterior connection electrode 317 is formed to be exposed atthe bottom surface of the thin film circuit layer 21 as shown in FIG. 7,signals can be supplied from the outside. By a peeling and transferringprocess performed only once on the transfer substrate 31, the thin filmcircuit layer 21 having an inverted structure with respect to thetransfer substrate 31 can be used as a thin film circuit of an organicEL pixel. In the case described above, compared to the case in which anon-inverted structure is formed by performing a peeling andtransferring process twice with the use of a temporary transferringsubstrate, the number of steps can be advantageously decreased.

Accordingly, the lamination of thin film circuit layers may be performedby changing the number of layers in consideration of the laminationposition and the complicacy of circuit. For example, a second thin filmcircuit layer may be provided on a part of a first thin film circuitlayer. On a part of this second thin film circuit layer, a third thinfilm circuit layer may be further provided. In addition, a plurality ofsecond thin film circuit layers is provided on a first thin film circuitlayer. On said plurality of second thin film circuit layers, a thirdthin film circuit layer may be formed.

As described above, the structure of lamination of thin film circuitlayers may be variously formed, and an optional structure may beselected in accordance with requirements.

FIGS. 8A-8E include schematics for illustrating examples of electronicsystems using electro-optical apparatuses provided with various thinfilm circuit devices according to the present invention. The thin filmcircuit devices described above are used, for example, forelectro-optical apparatus, drive apparatus, and control apparatus. In anaspect of the present invention, the electro-optical apparatus generallyindicate apparatus each provided with an electro-optical element havingan electrical function of emitting light or changing the state of lightincident from the outside, and the electro-optical apparatus include anapparatus that emits light by itself and an apparatus that controlsexterior light passing therethrough. For example, as the electro-opticalelements, there may be mentioned liquid crystal elements,electrophoretic elements composed of a dispersion medium andelectrophoretic particles dispersed therein, the EL (electroluminescent)elements described above, and electron-emitting elements emitting lightby colliding electrons against a light-emitting plate, the electronsbeing generated by application of an electric field, and displayapparatuses provided with the elements mentioned above are calledelectro-optical apparatus.

As the electronic system, for example, there may be mentioned anelectronic system which uses an electro-optical apparatus provided witha thin film circuit laminate device as a display portion, and in anaspect of the present invention, video cameras, televisions, largescreen display systems, mobile phones, personal computers, portableinformation systems (so-called PDA), and the like may be mentioned asthe electronic systems.

FIG. 8A shows a mobile phone as one example of the electronic system. Amobile phone 510 is composed of an antenna part 511, a voice output part512, a voice input part 513, an operation part 514, and anelectro-optical apparatus 51 including a thin film circuit laminatedevice. As described above, the thin film circuit laminate device of anaspect of the present invention can be used as a display portion of themobile phone 510. FIG. 8B shows a video camera as one example of theelectronic system, and a video camera 520 is composed of animage-receiving part 521, an operation part 522, a voice input part 523,and the electro-optical apparatus 51 including a thin film circuitlaminate device. As described above, the thin film circuit laminatedevice of an aspect of the present invention can be used as a viewfinderand/or a display portion. FIG. 8C shows a portable personal computer asone example of the electronic system, and a portable personal computer530 is composed of a camera part 531, an operation part 532, and theelectro-optical apparatus 51 including a thin film circuit laminatedevice. As described above, the thin film circuit laminate device of anaspect of the present invention can be used as a display portion.

FIG. 8D shows a headmount display as one example of the electronicsystem. A headmount display 540 is composed of a band 541, an opticalsystem container 542, and the electro-optical apparatus 51 including athin film circuit laminate device. As described above, the thin filmcircuit laminate device of an aspect of the present invention can beused as an image display apparatus. FIG. 8E shows a rear projector asone example of the electronic system, and a projector 550 is composed ofa light source 552, a synthetic optical system 553, a mirror 554, amirror 555, a screen 556, and the electro-optical apparatus 51 includinga thin film circuit laminate device, which are contained in a case 551.As described above, the thin film circuit laminate device of an aspectof the present invention can be used as an image display apparatus. FIG.8F shows a front projector as one example of the electronic system. Aprojector 560 has a case 562 in which an optical system 561 and theelectro-optical apparatus 51 including a thin film circuit laminatedevice are contained, and in the front projector, an image can bedisplayed on a screen 563. As described above, the electro-opticalapparatus of an aspect of the present invention can be used as an imagedisplay apparatus.

In addition to the examples described above, the thin film circuitlaminate device of an aspect of the present invention can be applied tovarious electronic systems. For example, the thin film circuit laminatedevice of an aspect of the present invention may be used for facsimilemachines provided with a display function, viewfinders of digitalcameras, portable televisions, DSP systems, PDA, electronic notebooks,electric bulletin boards, advertisement display systems, and the like.

As has thus been described, according to an aspect of the presentinvention, a thin film circuit device can be formed by laminating thinfilm circuit layers to each other using a peeling and transferringmethod. In addition, by using a laminated thin film circuit layers, anarea of the substrate in which circuits are formed can be decreased ascompared to that in the case in which individual circuits are directlyformed on the substrate. Furthermore, by laminating thin film circuitsto each other, the distance of signal transmittance between the circuitscan be decreased.

1. A thin film circuit device, comprising: an underlayer; a thin filmcircuit layer formed on the underlayer and functioning as an electricalcircuit; and a connection electrode which penetrates a part of theunderlayer so as to be exposed approximately flush with a surface of theunderlayer at a side opposite to the thin film circuit layer and whichconnects the thin film circuit layer to an exterior circuit.
 2. The thinfilm circuit device according to claim 1, further comprising: a firstprotective layer covering at least a part of the thin film circuit layerfor protection; and a connection electrode which penetrates a part ofthe first protective layer so as to be exposed approximately flush witha surface of the first protective layer at the side opposite to the thinfilm circuit layer and which connects the thin film circuit layer to anexterior circuit.
 3. A thin film circuit device, comprising: a heatresistant first substrate; a peeling layer which is formed on the firstsubstrate and which is to be peeled away by energy applied thereto; aninsulating underlayer formed on the peeling layer; a thin film circuitlayer formed on the underlayer; a first protective layer formed on thethin film circuit layer; and a connection electrode which penetrates apart of the underlayer to be in contact with the peeling layer and whichis to be exposed to connect the thin film circuit layer to an exteriorcircuit when the peeling layer is removed away.
 4. The thin film circuitdevice according to claim 3, further comprising: a second protectivelayer between the peeling layer and the underlayer.
 5. A thin filmcircuit device, comprising: a first thin film circuit layer having afirst thin film circuit formed between an underlayer and a firstprotective layer and a lower connection electrode connected to the firstthin film circuit and exposed at a part of the bottom surface of theunderlayer; and a second thin film circuit layer having a second thinfilm circuit formed between an underlayer and a first protective layer,an upper connection electrode connected to the second thin film circuitand exposed at a part of the top surface of the first protective layer,and a lower connection electrode connected to the second thin filmcircuit and exposed at a part of the bottom surface of the underlayer,the first thin film circuit layer and the second thin film circuit layerbeing laminated to each other, and the lower connection electrode of thefirst thin film circuit layer being connected to the upper connectionelectrode of the second thin film circuit layer.
 6. The thin filmcircuit device according to claim 5, the lower connection electrode andthe upper connection electrode being connected to each other with ananisotropic conductive material or a conductive adhesive.
 7. Anelectro-optical apparatus, comprising: the thin film circuit deviceaccording to claim
 1. 8. An electronic system, comprising: theelectro-optical apparatus according to claim
 7. 9. A method tomanufacture a thin film circuit device, comprising: forming a first thinfilm circuit layer above a first circuit-forming substrate with apeeling layer provided therebetween, the first thin film circuit layerhaving one connection electrode on at least a surface thereof; forming asecond thin film circuit layer above a second circuit-forming substratewith a peeling layer provided therebetween, the second thin film circuitlayer having connection electrodes on one surface and another surfacethereof; peeling the first thin film circuit layer from the firstcircuit-forming substrate so that the first thin film circuit layer istransferred to a transfer substrate; bonding the second thin filmcircuit layer to the first thin film circuit layer transferred to thetransfer substrate so that one of said connection electrodes of thesecond thin film circuit layer overlaps the connection electrode of thefirst thin film circuit layer; and peeling the second thin film circuitlayer from the second circuit-forming substrate so that the second thinfilm circuit layer is transferred to the first thin film circuit layerto form a laminate.
 10. The method to manufacture a thin film circuitdevice, according to claim 9, further comprising forming at least one ofthe first thin film circuit layer and the second thin film circuit layerby: forming an underlayer on the peeling layer provided on thecircuit-forming substrate; forming a thin film circuit on theunderlayer; forming a contact hole penetrating a part of the underlayerto expose the peeling layer; forming an electrode wire between thecontact hole and the thin film circuit; and forming a first protectivelayer on the thin film circuit and the electrode wire.
 11. The method tomanufacturing a thin film circuit device, according to claim 9, furthercomprising: forming a second protective layer between the peeling layerand the thin film circuit layer; and removing the second protectivelayer after the thin film circuit layer is peeled away to transfer.